JP5935727B2 - Sheet material conveyance path and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet material conveyance path and an image forming apparatus.

  Patent Document 1 includes a guide plate having ribs extending along the sheet conveyance direction, and a plurality of ribs are formed corresponding to the sheet size to be conveyed, and one or a plurality of ribs are formed on each rib. A technique related to a sheet conveying device in which a notch is formed is disclosed. In this prior art, the height of the rib adjacent to the downstream side in the transport direction with the notch interposed therebetween is lower than the height of the rib adjacent to the upstream side.

  Patent Document 2 includes a toner image forming unit that forms a toner image on a recording medium such as a sheet to be conveyed, and a fixing unit that includes a heating roller and a pressing roller that heat and fix the toner image on the recording medium. Techniques relating to a conveyance guide device for guiding the leading end of a recording medium that has been heat-fixed in an image forming apparatus provided are disclosed. In this prior art, a conveyance guide member having a guide surface with which the leading end of the recording medium is slidably contacted on the discharge side of the heating roller is disposed, and the guide surface of the conveyance guide member is disposed on the nip between the heating roller and the pressure roller. It is formed on a curved surface in a direction opposite to the curl direction of the recording medium ejected from the portion.

Japanese Patent Laid-Open No. 04-31542 JP 09-281826 A

  An object of the present invention is to smoothly convey a sheet material even if the leading end of the sheet material is curved.

The invention according to claim 1 is provided on the downstream side in the transport direction with respect to the transport roller forming a pair for transporting the sheet material and the rotation axis of one of the transport rollers, and in the side view, the upstream end is the one of the one of the transport rollers. A downstream end located on the side opposite to the other transport roller with respect to the transport path from the rotational axis of the transport roller and located on the other transport roller side from the upstream end to the other transport roller A guide section that guides the sheet material to the transport path side, the one transport roller is a drive roller, and the upstream end of the guide section is It is located closer to the rotation axis than the outer peripheral surface of the drive roller.

According to a second aspect of the present invention, there is provided a fixing device for fixing a developer image to the sheet material while conveying the sheet material by a heating member and a pressure member, and the sheet material on which the developer image is fixed by the fixing device. The sheet material conveyance path according to claim 1, wherein the sheet is conveyed with the surface on the pressure member side serving as the guide portion side.

  According to the first aspect of the present invention, compared with the case where the upstream end of the guide portion is located on the other conveyance roller side with respect to the conveyance path with respect to the rotation axis of one conveyance roller, Even if the tip is curved, the sheet material can be smoothly conveyed.

Further, the upstream end of the guiding portion is compared with the case which is located outside the rotation axis than the outer peripheral surface of the drive roller, the upstream end of the guiding portion be leading edge of the sheet material is curved It is possible to suppress the conveyance failure due to the contact of the tip of the sheet material with the portion, and to convey the sheet material smoothly.

According to the second aspect of the present invention, the sheet material, on which the developer image is fixed by the fixing device, is conveyed as the guide portion side, so that the sheet material whose tip is curved by fixing can be smoothly smoothed. Can be conveyed.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is a perspective view which shows the inner side guide part which comprises the inner side of the inversion conveyance path of one embodiment of this invention. It is a perspective view which shows the outer side guide part which comprises the outer side of the reverse conveyance path of one embodiment of this invention. It is a side view which shows the conveyance rib arrange | positioned between the conveyance roller pair of the reverse conveyance path of one Embodiment of this invention. It is a side view which shows the conveyance rib arrange | positioned in the width direction outer side of the conveyance roller pair of the reverse conveyance path of one embodiment of this invention. FIG. 6 is a side view illustrating a state where a recording medium with a curled tip is conveyed to the reverse conveyance path of FIG. 5. FIG. 10 is a side view showing a state in which a recording medium having a curved tip is conveyed to a reverse conveyance path of a comparative example to which the present invention is not applied.

An example of an image forming apparatus according to an embodiment of the present invention will be described.
<Overall configuration>
First, the configuration of the image forming apparatus 10 according to the present embodiment will be described. FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus 10 according to the present embodiment. Note that an arrow UP shown in the drawing indicates a vertically upward direction.

  An image forming apparatus 10 according to the present embodiment illustrated in FIG. 1 is a double-sided image forming apparatus capable of forming images on both sides of a sheet-like recording medium P as an example of a sheet material. The image forming apparatus 10 includes an image forming apparatus main body 11 in which each component is housed.

  Inside the image forming apparatus main body 11, a storage unit 12 that stores a recording medium P such as recording paper or an OHP sheet, an image forming unit 14 that forms an image on the recording medium P, and a storage unit 12 to an image forming unit. 14, a transport unit 16 that transports the recording medium P to 14, and a control unit 20 that controls the operation of each unit of the image forming apparatus 10. In addition, a discharge unit 18 for discharging the recording medium P on which an image is formed by the image forming unit 14 is provided on the upper portion of the image forming apparatus main body 11.

  The image forming unit 14 includes image forming units 22Y, 22M, 22C, and 22K (hereinafter referred to as 22Y to 22K) that form toner images of colors of yellow (Y), magenta (M), cyan (C), and black (K). The intermediate transfer belt 24 to which the toner images formed by the image forming units 22Y to 22K are transferred, and the first transfer roller for transferring the toner images formed by the image forming units 22Y to 22K to the intermediate transfer belt 24 26 and a second transfer roller 28 that transfers the toner image transferred to the intermediate transfer belt 24 by the first transfer roller 26 from the intermediate transfer belt 24 to the recording medium P. The image forming unit 14 is not limited to the above-described configuration, and may be another configuration as long as it forms an image on the recording medium P.

  The image forming units 22 </ b> Y to 22 </ b> K are arranged side by side at the center in the vertical direction of the image forming apparatus main body 11 while being inclined with respect to the horizontal direction. Each of the image forming units 22Y to 22K includes a photoreceptor 32 that rotates in one direction (for example, the clockwise direction in FIG. 1). Since the image forming units 22Y to 22K are configured in the same manner, the reference numerals of the respective parts of the image forming units 22M, 22C, and 22K are omitted in FIG.

  Around each photoconductor 32, a charging roller 23 as an example of a charging device for charging the photoconductor 32 and a photoconductor 32 charged by the charge roller 23 are exposed in order from the upstream side in the rotation direction of the photoconductor 32. The exposure device 36 that forms an electrostatic latent image on the photoconductor 32, the developing device 38 that develops the electrostatic latent image formed on the photoconductor 32 by the exposure device 36 to form a toner image, and the photoconductor 32. And a removing member 40 for removing the toner remaining on the photosensitive member 32.

  The exposure device 36 is configured to form an electrostatic latent image based on the image signal sent from the control unit 20. Examples of the image signal sent from the control unit 20 include an image signal acquired by the control unit 20 from an external device.

  The developing device 38 includes a developer supply body 38A that supplies the developer to the photoconductor 32, and a plurality of transport members 38B that transport the developer applied to the developer supply body 38A while stirring.

  The intermediate transfer belt 24 is formed in an annular shape and is disposed on the upper side of the image forming units 22Y to 22K. On the inner circumferential side of the intermediate transfer belt 24, winding rollers 42 and 44 around which the intermediate transfer belt 24 is wound are provided. The intermediate transfer belt 24 is circulated and moved (rotated) in one direction (for example, counterclockwise in FIG. 1) while being in contact with the photosensitive member 32 by rotating one of the winding rollers 42 and 44. It has become. The winding roller 42 is a counter roller that faces the second transfer roller 28.

  The first transfer roller 26 faces the photoconductor 32 with the intermediate transfer belt 24 interposed therebetween. A space between the first transfer roller 26 and the photoconductor 32 is a first transfer position where the toner image formed on the photoconductor 32 is transferred to the intermediate transfer belt 24.

  The second transfer roller 28 faces the winding roller 42 with the intermediate transfer belt 24 interposed therebetween. A space between the second transfer roller 28 and the winding roller 42 is a second transfer position where the toner image transferred to the intermediate transfer belt 24 is transferred to the recording medium P.

  The transport unit 16 is disposed along the transport path 48 and is transported along a transport roller 48 that transports the recording medium P stored in the storage unit 12, a transport path 48 that transports the recording medium P that is transported to the transport roller 46. A plurality of transport rollers 50 are provided for transporting the recording medium P delivered by the rollers 46 to the second transfer position.

  The image forming apparatus main body 11 is provided with a fixing device 60 for fixing the toner image transferred to the recording medium P by the second transfer roller 28 to the recording medium P, on the downstream side in the transport direction from the second transfer position. The fixing device 60 is removable in the manufacturing process and cannot be removed by the user. The fixing device 60 includes a discharge roller 52 that discharges the recording medium P on which the toner image is fixed to the discharge unit 18.

  The fixing device 60 is provided with a heating roller 64 and a pressure belt 66 as an example of a fixing member for fixing the toner image to the recording medium P.

  The heating roller 64 includes a cylindrical cylindrical member 64A that is rotatably supported by the fixing device 60, and a heating source 64B such as a halogen lamp provided in the internal space of the cylindrical member 64A. The pressure belt 66 is formed in an annular shape and is rotatably supported by the fixing device 60 at a position facing the heating roller 64.

  The heating roller 64 and the pressure belt 66 rotate with the width direction (hereinafter referred to as the width direction) orthogonal to the conveyance direction (hereinafter referred to as the conveyance direction) of the recording medium P as the rotation axis direction and along the recording medium width direction. And has a length.

  In the heating roller 64 and the pressure belt 66, the heating roller 64 is driven to rotate and the pressure belt 66 is driven and rotated by the heating roller 64, so that the recording medium P onto which the toner image is transferred is sandwiched and conveyed. It has a configuration. As described above, the recording medium P conveyed by being sandwiched between the heating roller 64 and the pressure belt 66 is heated by the heating roller 64 and is also pressurized by the pressure belt 66 so that the image is fixed. It has become.

  The fixing device 60 is provided with a pair of discharge rollers 52 for discharging the recording medium P on which the toner image is fixed by the heating roller 64 and the pressure belt 66 from the fixing device 60 to the discharge unit 18. The pair of discharge rollers 52 includes a driven roller 52A and a driving roller 52B disposed below the driven roller 52A.

  In order to form an image on both sides of the recording medium P, the image forming apparatus main body 11 has a reverse conveyance path 70 that sends back a recording medium having an image formed on one side to a transfer position (image forming position). The reverse conveyance path 70 will be described later.

  Further, the fixing device 60 is provided with an introduction path 49 for introducing the fixed recording medium P on which the image is fixed to the reverse conveyance path 70. The introduction path 49 is configured to guide the fixed recording medium P fed back by the reverse rotation of the discharge roller 52 to the reverse conveyance path 70.

  As described above, in the image forming apparatus 10, the recording medium P having an image formed on one side can be reversed and sent back to the conveyance path 48 by the introduction path 49 and the reverse conveyance path 70.

<Image forming operation>
Next, an image forming operation for forming an image on the recording medium P in the image forming apparatus 10 according to the present embodiment will be described.

  In the image forming apparatus 10 according to the present embodiment, the recording medium P sent out from the storage unit 12 by the sending roller 46 is sent to the second transfer position by the plurality of transport rollers 50.

  On the other hand, in the image forming units 22 </ b> Y to 22 </ b> K, the photosensitive member 32 charged by the charging roller 23 is exposed by the exposure device 36 to form an electrostatic latent image on the photosensitive member 32. The electrostatic latent image is developed by the developing device 38 to form a toner image on the photoreceptor 32. The color toner images formed by the image forming units 22Y to 22K are superimposed on the intermediate transfer belt 24 at the first transfer position to form a color image. Then, the color image formed on the intermediate transfer belt 24 is transferred to the recording medium P at the second transfer position.

  The recording medium P to which the toner image has been transferred is conveyed to the fixing device 60, and the transferred toner image is fixed by the fixing device 60. When an image is formed only on one side of the recording medium P, the recording medium P is discharged to the discharge unit 18 by the discharge roller 52 after the toner image is fixed.

  In the case of forming an image on both sides of the recording medium P, after the image is formed on one side, the recording medium P is fed from the introduction path 49 to the reverse conveyance path 70 by the reverse rotation of the discharge roller 52. Further, the sheet is fed from the reverse conveyance path 70 to the conveyance path 48, an image is formed on the opposite surface side in the same manner as described above, and an image is formed on both surfaces of the recording medium P. A series of image forming operations are performed as described above.

<Reverse conveying path>
Next, the reverse conveyance path 70 will be described.

  A path along which the recording medium P is transported through the reverse transport path 70 is illustrated as a transport path S. Further, driven rollers 82 and 92 (to the left in FIG. 1) described later with respect to the conveyance path S are “inside”, and driving rollers 84 and 94 (to the right in FIG. 1) with respect to the conveyance path S are “outside”. (The opposite side of the driven roller 92).

  As shown in FIG. 1, a conveyance roller pair 80 including a driving roller 84 and a driven roller 82 is provided in a curved portion 71 where the conveyance direction in the upper part of the reverse conveyance path 70 changes from the lateral direction to the downward direction. ing. In addition, the linear straight portion 72 on the downstream side in the conveyance direction of the conveyance roller pair 80 in the reverse conveyance path 70 is provided with a conveyance roller pair 90 including a driving roller 94 and a driven roller 92.

  As shown in FIGS. 2 and 3, the transport roller pairs 80 and 90 are provided at two positions spaced in the width direction orthogonal to the transport direction. The interval in the width direction of each pair of conveying rollers 80 and 90 is set to be narrower than the width of the smallest recording medium P on which the image forming apparatus 10 forms an image.

  In addition, the two drive rollers 84 provided at intervals in the width direction are provided on a single rotation shaft (drive shaft) 86 whose axial direction is the width direction. Similarly, two drive rollers 94 provided at intervals in the width direction are also provided on a single rotation shaft (drive shaft) 96 having the width direction as an axial direction.

  The rotating rollers 86 and 96 are rotated by a driving mechanism (not shown), so that the driving rollers 84 and 94 are rotated. Then, the recording medium P is sandwiched between the driven rollers 82 and 92 and conveyed through the reverse conveyance path 70.

  As shown in FIG. 2, the inner side of the reverse conveyance path 70 is configured by an inner guide portion 17 (see also FIG. 1). The inner guide part 17 has a configuration in which a plurality of short ribs 15 are formed on the plate surface along the transport direction.

  As shown in FIG. 3, the outer side of the reverse conveyance path 70 is configured by an outer guide portion 100 (see also FIG. 1). The outer guide part 100 is composed of a plurality of plate-shaped transport ribs 102 and 110 along the transport direction. The plate-shaped transport ribs 102 and 110 are arranged such that the plate thickness direction is a width direction orthogonal to the transport direction, and are provided at intervals in the width direction.

  In addition, the conveyance rib 110 is arrange | positioned on the width direction outer side rather than the conveyance roller pair 90 provided at intervals in the width direction, and the conveyance rib 102 is arranged between the conveyance roller pair 90.

  As shown in FIGS. 4 and 5, a reverse conveyance path 70 is formed between the end surfaces 108 and 118 of the plate-shaped conveyance ribs 102 and 110 and the short rib 15 of the inner guide portion 17. The transport ribs 102 and 110 are formed with recesses 104 and 114 for escaping the rotation shaft 96 of the drive roller 94.

  As shown in FIG. 5, a guiding portion 120 is formed on the downstream side of the recess 114 of the transport rib 110 in the transport direction.

  When viewed from the side as viewed in the direction of the rotational axis 94A of the drive roll 94, the upstream end 120A (boundary portion with the recess 114) of the guide portion 120 is located with respect to the transport path S more than the rotational axis 94A of the drive roller 94 It is located on the outside (opposite side of the driven roller 92). More specifically, it is conveyed more than a straight line 93 that passes through the rotational axis 94A of the drive roller 94 and is orthogonal to the straight line 91 that connects the rotational axis 92A of the driven roller 92 and the rotational axis 94A of the drive roller 94. It is located outside the path S (on the opposite side of the driven roller 92).

  The guiding portion 120 then moves from the upstream end portion 120A to the downstream end portion 120B (boundary portion with the end surface 118) located on the transport path S side (driven roller 92 side) with respect to the rotation axis 94A (straight line 93). It is comprised so that it may continue. Note that the leading end portion of the recording medium P that hits the guide portion 120 is guided to the transport path S side (driven roller 92 side) (see FIG. 6).

  In addition, when viewed from the side, the upstream end 120A is located closer to the rotation axis 94A (upstream in the conveying direction) than the outer peripheral surface 94S of the drive roller 94.

  The guide part 120 has a configuration including a curved part 122 connected from the upstream end part 120A (concave part 114) and a straight part 124 connected from the curved part 122 to the downstream end part 120B (end surface 118).

  An extension line 121 of the upstream end 120A of the guide portion 120 (tangent to the upstream end 120A of the curved portion 122) 121 connects the rotation axis 92A of the driven roller 92 and the rotation axis 94A of the drive roller 94. The angle θ1 with respect to the straight line 91 is set to be 90 °. The angle θ1 is not necessarily 90 °, and may be set so that the angle θ1 is in the range of 85 ° to 90 °.

  Further, the radius R1 of the curved portion 122 of the guide portion 120 is set to be 10 mm or more. Further, the opening angle θ2 of the bending portion 122 is set to be 140 ° or more.

<Action and effect>
Next, the operation and effect of this embodiment will be described.

  As described above, when an image is formed on both sides of the recording medium P, after the image is formed on one side by the fixing device 60, the recording medium P is removed from the introduction path 49 by the reverse of the discharge roller 52. It is sent to the reverse conveyance path 70.

  At both ends in the conveyance direction of the recording medium P after fixing, a curved PC that bends to the back surface PB side opposite to the fixing surface PA on which the image is fixed, that is, to the back surface PB side of the pressure belt 66 side of the fixing device 60 is generated. (See FIG. 6). Then, the recording medium P is sent to the reverse conveyance path 70 in a state where the curved PC is generated at the leading end in the conveyance direction.

  In the reverse conveyance path 70, the curved PC is not corrected on the outer side in the width direction than the two conveyance roller pairs 80 and 90 arranged at intervals in the width direction in the recording medium P, and the conveyance is performed in a state where the curved PC is generated. Is done.

  Here, the conveyance rib 510 as a comparative example to which the present invention shown in FIG. 7 is not applied will be described. The upstream end portion 520A (boundary portion with the concave portion 114) of the guide portion 520 of the transport rib 510 of the comparative example is located on the inner side (driven roll) with respect to the transport path S than the rotation axis 94A (straight line 93) of the drive roller 94. 92 side). Further, the extension line 521 of the upstream end 120A of the guide portion 520 has an angle θ1 with respect to the straight line 91 of about 60 °.

  In the case of the guiding portion 520 of this comparative example, if the bending PC is large, the collision angle θ3 of the guiding portion 520 at the leading end of the bending PC increases, and the leading end of the recording medium P is guided to the guiding portion 520 as indicated by a two-dot broken line. The tip may be bent due to being caught on. Further, the recording medium P may be jammed in the transport path due to the bending of the tip (JAM may occur).

  On the other hand, as shown in FIGS. 5 and 6, in the guide portion 120 of the present embodiment, the upstream end portion 120 </ b> A is located with respect to the transport path S rather than the rotational axis 94 </ b> A (straight line 93) of the drive roller 94. Since it is located on the outer side, the collision angle θ3 (see FIG. 6) of the guiding portion 120 at the tip of the curved PC is smaller than in the comparative example.

  Therefore, as indicated by a two-dot broken line in FIG. 6, the leading end of the recording medium P is not easily caught by the guiding portion 120, and as a result, the leading end breakage is prevented. That is, the guiding unit 120 of this embodiment is less likely to cause a conveyance failure and is smoothly conveyed as compared with the guiding unit 520 of the comparative example.

  In addition, since the upstream end 120A of the guide unit 120 is located on the rotation axis 92A side (upstream in the transport direction) with respect to the outer peripheral surface 94S of the drive roller 94, the leading end of the curved PC of the recording medium P is the guide unit. The conveyance failure due to the contact with the upstream end 120A of the 120 is prevented, and the recording medium P is smoothly conveyed.

  Further, since the back surface PB on the pressure belt 66 side of the recording medium P on which the developer image has been fixed by the fixing device 60 is conveyed as the guiding portion 120 side, the recording medium P in which the curved PC is generated by the fixing. Even if it is transported smoothly.

<Others>
In addition, this invention is not limited to the said embodiment.

  For example, in the above-described embodiment, the present invention is applied to the conveyance ribs 110 on the outer side in the width direction with respect to the conveyance roller pair 90 arranged at intervals in the width direction orthogonal to the conveyance direction. The present invention may also be applied to the transport rib 102.

  In the above-described embodiment, the present invention is applied to the reverse conveyance path 70 that sends back a recording medium having an image formed on one side for forming an image on both sides of the recording medium P to a transfer position (image forming position). It is not limited to this. The present invention can be applied to any conveyance path that conveys a recording medium.

  For example, the configuration of the image forming apparatus is not limited to the configuration of the above-described embodiment, and various configurations can be employed. In the above embodiment, the image forming apparatus forms an image on a recording medium by an electrophotographic method. However, the present invention is not limited to this. The present invention can also be applied to an image forming apparatus such as an inkjet method or a thermal transfer method.

  Further, the present invention can be applied to apparatuses other than the image forming apparatus, for example, an image reading apparatus. That is, the present invention can be applied to all conveying apparatuses that convey sheet materials.

  Furthermore, it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from the summary of this invention.

10 Image forming apparatus 90 Conveying roller pair (conveying roller forming a pair)
94 Driving roller 94A Rotating shaft center 94S Outer peripheral surface 60 Fixing device
64 Heating roller (an example of a heating member)
66 Pressure belt (example of pressure member)
70 Reverse transport path (example of transport path)
120 Guide part 120A Upstream end 120B Downstream end
P Recording medium (an example of sheet material)
S Transport route

Claims (2)

A pair of transport rollers for transporting the sheet material;
Provided downstream of the rotation axis of one of the conveyance rollers in the conveyance direction, and when viewed from the side, the upstream end is opposite to the other conveyance roller with respect to the conveyance path of the rotation axis of the one conveyance roller And a guiding portion that leads from the upstream side end portion to the downstream side end portion located on the other conveying roller side with respect to the rotation axis, and guides the sheet material to the conveying path side. ,
Equipped with a,
The one conveying roller is a driving roller,
The upstream end portion of the guide portion is a sheet material conveyance path that is located closer to the rotation axis than the outer peripheral surface of the drive roller in a side view .   A fixing device for fixing a developer image to the sheet material while conveying the sheet material by a heating member and a pressure member;
  The sheet material transport path according to claim 1, wherein the sheet material on which the developer image is fixed by the fixing device is transported with the surface on the pressure member side being the guiding portion side;
  An image forming apparatus comprising:

Images